Thermo‐mechanical behavior of ball grid packages with different solder ball grid patterns investigated through moiré interferometry

Abstract

Plastic ball‐grid array (PBGA) package assembly comprises various materials with different thermo‐mechanical properties, and the solder ball‐grid patterns can significantly influence the package deformation and solder ball stress. This study utilizes moiré interferometry to investigate the deformation behavior of wire bonded plastic ball‐grid array (WB‐PBGA) packages under varying temperatures. Real‐time moiré interferometry experiments were conducted to capture fringe patterns representing package deformation at different temperature stages. Experiments were conducted for three different wire bonded plastic ball‐grid array packages with distinct solder ball array configurations: full grid patterns (WB‐PBGA‐FG) and perimeter patterns with/without central connections (WB‐PBGA‐PC/P). The analysis revealed considerable variations in thermal strain distribution and positioning of the critical solder ball within the package assembly, depending on the solder ball‐grid pattern. Among these wire bonded plastic ball‐grid array packages, WB‐PBGA‐P/C exhibited the most substantial bending deformation, experiencing the highest effective strain, which directly impacts solder ball failure. These findings emphasize the importance of solder ball‐grid patterns in understanding the deformation behavior and reliability of WB‐PBGA packages under varying temperature conditions.